1. Field of the Invention
The present invention relates to an image forming apparatus, such as a photocopier, a printer, a facsimile machine, and the like, and in particular, to an image forming apparatus having a plurality of parallel mounted sheet conveying paths formed by a plurality of movable sheet guide members.
2. Discussion of the Background
In an image forming apparatus such as a photocopier, a printer, a facsimile machine, and the like, the apparatus is increasingly requested to be provided with multiple functions, reduced in size, and operated at high speeds. In order to satisfy these requests, constructions of conveying paths for conveying recording materials with an image fixed thereto become particularly complicated. To achieve high speed operation, a feeding interval of recording materials (sheet interval) is reduced, or a feeding speed (linear velocity) is increased. The image forming apparatus is also variously devised in consideration of an occurrence of sheet jamming so that a user can easily remove a jammed recording material or sheet in each conveying path of the apparatus. However, depending on an installation place or configuration of the apparatus, jam removing may not be able to be performed from the outside of the apparatus.
Generally, a pair of feeding rollers, a drive roller, and a driven roller for feeding the recording materials are arranged facing a conveying path such that the drive roller and the driven roller abut on or press against each other. In an image forming apparatus in which stacked documents are taken in, in one mode the documents are stacked with surfaces to be read facing downward, and are taken in from a lowermost or uppermost document. In another mode, the documents are stacked with surfaces to be read facing upward, and are taken in from the lowermost or uppermost document. In these modes, when the uppermost stacked document with its surface to be read facing upward or the lowermost stacked document with its surface to be read facing downward is first taken in or when duplicate photocopying is performed, a reversing unit is provided. In order to achieve high speed operation of an image forming apparatus provided with a reversing unit, the interval between the recording materials (sheet interval) is reduced by the constructions in which a conveying path connecting a fixing device and the reversing unit and a conveying path connecting the reversing unit and a sheet discharging section are arranged in parallel, and a feeding path and a discharging path of the recording materials relative to the reversing unit are independently provided.
In an image forming apparatus provided with a reversing unit, the reversing unit is movably mounted on a main body of the image forming apparatus for removing a jammed sheet, but the conveying paths are not released with the movement of the reversing unit. Therefore, when the reversing unit is pulled out with the sheet jammed therein, the sheet after fixing is torn and left in the conveying paths or the reversing unit. Accordingly, a user has difficulties in removing the jammed sheet completely.
To solve the above-mentioned problem, the present applicant proposed an image forming apparatus in which conveying paths are arranged in parallel and are opened/shut inside the apparatus because a part of the conveying paths are formed by guide members disposed movably between a sheet guide position in which recording materials are guided along the conveying paths and a sheet jam removing position in which the conveying paths are opened for removal of a jammed sheet. Further, in the image forming apparatus, it is constructed that the guide members are movable by a pressing protrusion provided on the inner surface of an exterior cover, so that a plurality of conveying paths arranged in parallel are opened when the exterior cover is opened.
The pressing protrusion fixed to the inner surface of the exterior cover is formed to be long and large enough to have sufficient size and strength to be inserted inside the main body of the image forming apparatus. Therefore, when the exterior cover is opened, the pressing protrusion gets in the way of jam removing operations. Moreover, when the guide members are in the sheet jam removing position, each conveying path is opened. In this case, however, when drive and driven rollers are not separated from each other, the jammed recording material is held between the rollers, and cannot be securely removed.